Deposit-control fuel additives effectively control deposits in carburetors, valves and fuel injectors of engine intake systems. Aminated polybutenes are widely employed as deposit control fuel additives. Aminated polybutenes are produced commercially by one of two processes which involve the reaction of chlorinated polybutene with an amine compound to produce a polybutene amine. These prior art processes, however, are characterized by the preparation of undesirable side-products and the creation of a large volume of contaminated aqueous waste streams.
U.S. Pat. No. 3,671,511, represents the primary process employed to produce polybutene amines today. It involves the reaction of chlorinated polybutene with an excess of polyamine, stripping the excess amine under vacuum, adding aromatic solvent to dilute the reaction mixture, and neutralizing the reaction mixture with aqueous sodium hydroxide. This step forms an emulsion which is broken by adding butanol. The phases are separated and the organic layer is washed several times before being dried and diluted with the desired solvent. This process has many disadvantages. One mole of excess amine per mole of reacted chlorinated polybutene is not recovered during stripping and ultimately is discarded in an aqueous layer. This results in the loss of a valuable raw material and is an economic and environmental disadvantage. The large volume of aqueous waste streams which contain amine, traces of aromatic solvent, and butanol represents a serious disposal problem and an economic as well as an environmental disadvantage. The butanol adds to the cost of the process since it cannot be recovered, and the necessity of performing multiple washes increases cycle time and manufacturing costs.
U.S. Pat. No. 3,454,555 describes the second most frequently used process to prepare polybutene amines and describes a system which overcomes many process-related problems associated with aqueous waste streams, lost butanol and amine, and multiple washes. It has a different problem, however which renders its product unacceptable to the customer. This process involves the reaction of an excess of polyamine with a chlorinated polybutene in the presence of sodium carbonate. When the reaction is completed the excess amine is removed by vacuum stripping, the reaction mixture is filtered to remove inorganic salts, and the product is diluted with a suitable solvent to the desired basic nitrogen level. The disadvantage of this process is that the carbon dioxide produced as a by-product reacts with the excess amine and the product to produce other by-products. These by-products are insoluble in the product and, with time, precipitate out to form a solid phase which creates many problems for the customer. Removal of this solid phase adds substantial cost.
Thus, the prior art has not provided a process for the production of polybutene fuel additives from chlorinated polybutenes which avoids the foregoing undesirable side reactions.